In cameras equipped with automatic functions to set focus or exposure parameters, there has evolved a convention on how to set these parameters. Commonly, the shutter button on these cameras is built as a two-stage button. When the user depresses the shutter button partially, the camera selects certain image-taking parameters, such as focus, aperture, exposure time, or sensor sensitivity, to values depending on what is in the camera's field of view at that moment. Then these parameters get locked. Together, aperture, exposure time, and sensor sensitivity determine the exposure value of the image to be taken, a concept well known in the art. The user can then ‘recompose’ the picture by pointing the camera in a different direction while holding the shutter button partially depressed. When the user is ready to take the picture, he depresses the shutter button fully, and a picture will be taken with the image-taking parameters that have been previously locked. This is an intuitive user interface that provides the photographer much creative control. However, the need for the user's tactile differentiation between a light press for the first step and a firm press for the second step also presents challenges when the user's fine motor control is impaired, for example by cold weather, gloves, or disability.
The method of partially depressing a shutter button to set and lock image-taking parameters and fully depressing that same shutter button to take the picture, as well as the terminology of ‘half press’ and ‘full press,’ have become so widespread that U.S. Pat. No. 7,738,029 specifically teaches the use of a “release button [that] is a two-step type which lends itself to a half press and full press” in the context of a method to measure exposure.
Recent years have seen the introduction of many multimedia devices, for example personal digital assistants, media players, and mobile telephones, that are also equipped with cameras capable of taking still images and/or videos. A few of these devices are equipped with a traditional two-step button specifically dedicated to use as a shutter button when the device is being used for taking pictures. However, this concept has not become very popular. In contrast to the traditional shape of dedicated cameras, many multimedia devices are more miniaturized and often have the shape of a very flat rounded cuboid. This makes is difficult to include a two-step button on the device's narrow lateral surfaces, which are the natural position for a shutter button. It is also harder for the user to feel the tactile difference between a half and a full press on a highly miniaturized button of a small multimedia device compared to the larger shutter button on a dedicated camera. FIG. 5 shows the flat cuboid shape of device 100 with the lowest-volume cuboid capable of enclosing the devices's shape and the two buttons 106 and 108 facing one of the cuboid's narrow faces.
Further, on a multimedia device where image taking is just one of many uses and not usually the primary one, it would be impractical to include a separate suite of buttons dedicated to image taking. U.S. Pat. No. 7,406,331 teaches the use of existing buttons normally used for communication functions on a mobile telephone equipped with a camera to control zooming the built-in camera and zooming pictures shown on the telephone's display. The benefit of this method is somewhat limited because most of the highly miniaturized cameras in mobile telephones do not have an optical zoom function. Adoption of this method appears to be limited if it has been adopted at all.
Instead, a different convention regarding the use of the volume buttons on mobile telephones has evolved. For example, recent versions of the popular iPhone®, made by Apple, Inc. of Cupertino, Calif., use the volume buttons as a shutter button. By pushing either volume button, the user can trigger an image to be taken.
U.S. Pat. No. 7,085,590 teaches the use of separate portrait and landscape display modes on mobile terminal devices with built-in camera functions.
We are now seeing the widespread adoption of touch-sensitive screens on mobile multimedia devices. A common method of setting exposure parameters on devices so equipped is by gestures to move the point of the picture which the autofocus should make sharpest or which the metering system should set aperture, exposure time, and/or sensitivity for. Shutter release is commonly accomplished by touching a specific area of the touchscreen or, less often, by pushing a button on the device. This method is counterintuitive for experienced photographers because instead of the traditional point/half press/recompose/full press sequence now one has to hold the device steady with one hand while making gestures on the screen with the other hand to set image-taking parameters and eventually take the picture. It is also difficult to hold the device steady with one hand between its narrow edges while making touch inputs on the screen with the other hand, in part because modern portable multimedia devices often are very narrow, making a steady hold difficult, and in part because the force of tapping on the screen is applied orthogonally to the force of the hand holding the device. This method of controlling exposure on a touch screen also makes use of this method very difficult for users that have use of only one hand, either because of disability or because they simply have their other hand occupied.
Thus, the methods of releasing the shutter on a camera known heretofore suffer from several disadvantages. The method commonly used for dedicated cameras requires a button with two separate contacts for half-press and full-press. Considerations of cost, size, and ergonomics make this approach impractical to implement in small multimedia devices such as cellular telephones. This method also is impractical when the user's tactile sensitivity is impaired by weather, gloves, or disability. The methods commonly used by the camera function on cellular telephones or other multimedia devices suffer from distinct disadvantages. They are counterintuitive for experienced photographers and demand that the device be held with one hand and the touchscreen manipulated with the other for setting image-taking parameters, which is difficult, time-consuming, and almost impossible to perform with one hand.